Method and apparatus for dividing wafers

Abstract

To quickly set processing conditions and efficiently divide wafers in a short amount of time. [Solution] A method for dividing a wafer W having a plurality of linear division starting points g formed on it at the division starting points g includes: an initial setting step of setting the size of the chips formed by the division of the wafer W; an angle setting step of setting the angle at which to bend the wafer W at the division starting points g; a holding step of holding the wafer W on a holding table 10; a clamping step of clamping the wafer W between a first bar 63 and a second bar 31 that contact one surface and the other surface of the wafer W held on the holding table 10; and a division step of bending the wafer W clamped between the first bar 63 and the second bar 31 in the clamping step by the angle set in the angle setting step with a pressing bar 62 to divide the wafer W at the division starting points g.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for dividing a wafer along a linear division starting point.

Background Art

[0002] For example, in the manufacturing process of semiconductor devices, the surface of a disc-shaped semiconductor wafer (hereinafter simply referred to as "wafer") is partitioned into a plurality of device regions by streets (division planned lines) formed in a grid pattern, and devices such as ICs and LSIs are respectively formed in each device region. Then, a plurality of chips can be obtained by dividing the wafer on which a large number of such devices are formed along the streets.

[0003] Here, as a method for dividing a wafer along a street, Patent Document 1 proposes a method of dividing the wafer with a modified layer as a division starting point by expanding a tape adhered to the wafer in which a modified layer is formed inside by irradiation of a laser beam.

[0004] However, even with the above method, in the case of wafers made of hard materials such as silicon carbide (SiC) and sapphire, it is difficult to divide the wafer by expanding the tape. For this reason, Patent Documents 2 to 4 propose a method of cutting the wafer along the street by pressing a cutting blade of a braking device against the wafer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0006] However, when using a breaking device to cut wafers, processing conditions such as the position and descent distance of the cutting blade must be set according to the chip size, wafer material, and thickness. This requires time to set the processing conditions, which presents a problem as it makes it difficult to efficiently cut wafers in a short amount of time.

[0007] The present invention has been made in view of the above problems, and its object is to provide a wafer splitting method and apparatus that can split wafers efficiently in a short time by setting processing conditions in a short time. [Means for solving the problem]

[0008] The wafer splitting method according to the present invention is a wafer splitting method for a wafer having a plurality of linear splitting starting points formed thereon, comprising: an angle setting step of setting an angle at which to bend the wafer at the splitting starting points; a clamping step of clamping the wafer by bringing a first bar into contact with one surface of the wafer and a second bar into contact with the other surface of the wafer; and a splitting step of bending the wafer clamped between the first bar and the second bar in the clamping step by an angle set in the angle setting step with a pressing bar to split the wafer at the splitting starting points.

[0009] Furthermore, the splitting apparatus according to the present invention is an apparatus for splitting a wafer having a plurality of linear splitting starting points formed on it at the splitting starting points, comprising: a first bar that contacts one surface of the wafer; a second bar that sandwiches the wafer and faces the first bar, contacting the other surface of the wafer; a clamping mechanism that moves the first bar and the second bar closer together or further apart; a pressing bar that presses one pressing position of the wafer, which is a predetermined distance away in the wafer plane from the wafer clamping position of the wafer by the first bar and the second bar; and the pressing bar in the wafer plane. The wafer is characterized by comprising: a first pressing bar moving mechanism that moves the pressing bar in a direction perpendicular to the extending direction; a second pressing bar moving mechanism that moves the pressing bar in a direction perpendicular to the surface direction of the wafer; an angle setting unit that sets the angle at which the wafer is bent at the dividing starting point; a pressing position setting unit that sets the pressing position of the wafer by the pressing bar; and a pressing bar movement amount calculation unit that calculates the amount of movement of the pressing bar by the second pressing bar moving mechanism from the pressing position set by the pressing position setting unit and the angle set by the angle setting unit. [Effects of the Invention]

[0010] According to the wafer splitting method of the present invention, which is carried out using the splitting apparatus of the present invention, a wafer held on a holding table is clamped by a first bar and a second bar at the splitting starting point, and the pressing bar is moved to a pressing position a predetermined distance away from the clamping position in the direction of the wafer surface to press one side of the wafer with the pressing bar, thereby splitting the wafer by bending it along the splitting starting point. The inventors have found that the bending angle of the wafer at the time of splitting is almost constant regardless of the chip size and depends on the material and thickness of the wafer.

[0011] Therefore, once the bending angle is set in the angle setting unit and the pressing position of the pressing bar is set in the pressing position setting unit, the distance from the dividing point to the pressing position of the pressing bar is determined, and the amount of movement of the pressing bar is calculated by the pressing bar movement amount calculation unit based on this distance and the bending angle of the wafer. This amount of movement of the pressing bar is proportional to the chip size, and the larger the chip size, the greater the amount of movement of the pressing bar, but the bending angle centered on the dividing point of the wafer is kept constant.

[0012] In other words, regardless of the chip size, the wafer is bent at a predetermined (constant) bending angle that is necessary and sufficient for division, centered on the division starting point. This prevents division errors caused by insufficient or excessive movement of the pressure bar, and ensures that the wafer is always reliably divided along the division starting point. Here, the amount of movement of the pressure bar is calculated based on the bending angle of the wafer and the distance from the division starting point to the pressing position of the pressure bar (a value determined by the chip size). As a result, the processing conditions can be set in a short time, and the wafer can be divided efficiently in a short time. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view of the dividing device according to the present invention. [Figure 2] This is a perspective view of the workset. [Figure 3] Figure 1 is a perspective view of the second bar mechanism of the splitting device shown in Figure 1. [Figure 4] This is a partial side cross-sectional view showing the holding step in the wafer splitting method according to the first embodiment of the present invention. [Figure 5] This is a partial side cross-sectional view showing the clamping step in a wafer splitting method according to the first embodiment of the present invention. [Figure 6] This is a partial side cross-sectional view showing the splitting step in the wafer splitting method according to the first embodiment of the present invention. [Figure 7] Figure 6 is a partially enlarged cross-sectional view showing the wafer splitting process. [Figure 8]It is a flowchart showing the procedure of the wafer splitting method according to the first embodiment of the present invention. [Figure 9] It is a partial side sectional view showing the holding step in the wafer splitting method according to the second embodiment of the present invention. [Figure 10] It is a partial side sectional view showing the clamping step in the wafer splitting method according to the second embodiment of the present invention. [Figure 11] It is a partial side sectional view showing the splitting step in the wafer splitting method according to the second embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0015] [Configuration of the Splitting Device] First, the configuration of the splitting device 1 according to the present invention will be described. In the following description, the directions of the arrows shown in FIG. 1 are taken as the X-axis direction (front-rear direction), Y-axis direction (left-right direction), and Z-axis direction (up-down direction), respectively.

[0016] The splitting device 1 according to the present embodiment is a device for splitting the wafer W shown in FIG. 2. The wafer W to be split is, for example, a thin disk-shaped member made of single-crystal silicon (Si). A metal film S (see FIG. 4) such as gold, silver, or copper is formed on its back surface (the lower surface in FIG. 2). Further, the surface of the wafer W (the upper surface in FIG. 2) is partitioned into a plurality of rectangular regions by mutually orthogonal streets (predetermined splitting lines) L1 and L2 arranged in a grid pattern, and devices D such as ICs and LSIs are formed in each rectangular region.

[0017] The wafer W, on which numerous devices D are formed on its surface, is then incorporated into the workset WS shown in Figure 2, and the splitting method according to the present invention is performed on the wafer W. Here, the workset WS is constructed by attaching the back surface (more precisely, the bottom surface of the metal film S) of the disc-shaped wafer W to a sheet T that is attached to a ring frame F made of metal (for example, made of SUS) and covers the circular opening of the ring frame F, thereby supporting the wafer W on the ring frame F via the sheet T and integrating the wafer W, ring frame F, and sheet T. In addition to silicon (Si), materials such as silicon carbide (SiC), glass, ceramics, and sapphire, which have high hardness, can be used as the material for the wafer W.

[0018] The splitting device 1 shown in Figure 1 comprises, as its main components, a ring-shaped holding table 10 for holding the ring frame F of the workset WS, a second bar mechanism 30 positioned inside the holding table 10, a pressing bar mechanism 60 provided on a gantry-type column 210 erected vertically on a base 200, a pressing bar lifting mechanism 70, an ultrasonic vibration application unit 80, an input device 90 for inputting initial data as initial setting values, and a control unit 100. The configurations of the holding table 10, the second bar mechanism 30, the pressing bar mechanism 60, the pressing bar lifting mechanism 70, the ultrasonic vibration application unit 80, the input device 90, and the control unit 100, which are the main components of the splitting device 1, will be described below.

[0019] (Retention table) The ring-shaped holding table 10 is rotatably mounted on the slider 21 of the horizontal movement mechanism 20, and two fixed clamps 11 and two movable clamps 12 are arranged on its upper surface at equal angular pitches (90° pitches) in the circumferential direction. Here, each fixed clamp 11 is fixed to the upper surface of the holding table 10, and each movable clamp 12 is equipped with a presser 12a that is movable along the radial direction (direction of the arrow in the figure) of the holding table 10.

[0020] The holding table 10 is rotatable about a vertical central axis by a rotation mechanism (not shown) and is reciprocally movable along the Y-axis by a horizontal movement mechanism 20. The horizontal movement mechanism 20 includes a pair of guide rails 22 laid parallel to each other along the Y-axis on a base 200, a rectangular plate-shaped slider 21 that can move along these guide rails 22, a rotatable ball screw 23 positioned along the Y-axis to the side of one (+Y-axis) guide rail 22, and a servo motor 24, which is a rotation drive source that can rotate in both forward and reverse directions, connected to one axial end of the ball screw 23. The other axial end of the ball screw 23 is rotatably supported on the base 200 via a bearing (not shown).

[0021] A rectangular block-shaped nut member 25 is attached to one side of the slider 21, and a ball screw 23 is screwed into and inserted through this nut member 25. Therefore, when the servo motor 24 is started and the ball screw 23 is rotated forward and backward, the nut member 25 that screws onto the ball screw 23 is attached, and the slider 21 can reciprocate along the pair of guide rails 22 in the Y-axis direction. As a result, the holding table 10 supported by the slider 21 can also reciprocate in the Y-axis direction. The servo motor 24 is equipped with an encoder 26 that detects the rotation direction and rotation speed of the servo motor, and this encoder 26 is electrically connected to the control unit 100.

[0022] (Second bar mechanism) The second bar mechanism 30, located inside the holding table 10, includes, as shown in Figure 3, four second bars 31 of different lengths arranged in a cross shape at equal angular pitches (90° pitches) in the circumferential direction of the outer circumference of the rotation axis 41, a second bar rotation mechanism 40 that intermittently rotates these second bars 31 by 90° increments, and a second bar lifting mechanism 50 that moves each second bar 31 up and down in the Z-axis direction. Note that the number of second bars 31 is not limited to four; any number is acceptable.

[0023] Each of the four second bars 31 is a rectangular plate-shaped member that is elongated in the X-axis direction. These are radially mounted on the outer circumference of a rotatable rotating shaft 41 that is arranged along the X-axis direction, and the tip of each second bar 31 has a stepped shape. The rotating shaft 41 is rotatably supported by a frame-shaped frame 42, and a driven gear 43 is connected to one axial end (+X-axis end) protruding from the frame 42. An electric motor 44, which is the rotation drive source, is mounted horizontally on one end of the frame 42 (the side on which the driven gear 43 is provided). A drive gear 45 is connected to the end of an output shaft 44a (not shown) that extends horizontally from the electric motor 44 and penetrates one side of the frame 42, and the drive gear 45 and the driven gear 43 mesh with each other. In this embodiment, the driven gear 43 and the drive gear 45 are of the same diameter.

[0024] Thus, the rotating shaft 41, electric motor 44, driven gear 43, and drive gear 45 constitute a second bar rotation mechanism 40 that rotates the four second bars 31. Therefore, when the electric motor 44 is started, the rotation of its output shaft (motor shaft) is transmitted to the rotating shaft 41 via the drive gear 45 and driven gear 43, which mesh with each other, and the rotating shaft 41 and the four second bars 31 attached thereto rotate intermittently at an angle of 90 degrees around the axis of the rotating shaft 41. The four second bars 31, which are of different lengths, are rotated at an angle of 90° by the second bar rotation mechanism 40, so that the length corresponding to the length of the streets L1 and L2 (see Figure 2) of the wafer W held on the holding surface of the holding table 10 is positioned vertically below the wafer W as shown in Figure 4, and clamps the lower surface of the wafer W together with the first bar 63 as described later.

[0025] Furthermore, the second bar lifting mechanism 50, which raises and lowers the four second bars 31, constitutes a clamping mechanism that raises the second bars 31 to clamp the wafer W together with the first bar 63. It includes a pair of guide rails 52 arranged along the Z-axis direction (up and down direction) on a vertically standing rectangular plate-shaped base 51, a rotatable ball screw 53 arranged along the Z-axis direction between these guide rails 52, and a servo motor 54, which is a rotation drive source connected to the lower end of the ball screw 53. The upper end of the ball screw 53 is rotatably supported by the base 51 via a bearing 55. In addition, a nut member (not shown) is attached to the frame 42, and the ball screw 53 is screwed into and inserted through this nut member.

[0026] Therefore, when the servo motor 54 is activated to rotate the ball screw 53 in the forward and reverse directions, the frame 42, to which a nut member (not shown) that screws onto the ball screw 53 is attached, moves up and down together with the rotating shaft 41 and the electric motor 44, and the four second bars 31, which are radially mounted on the rotating shaft 41, also move up and down along the Z-axis direction. The servo motor 54 is equipped with an encoder 56 that detects the rotation direction and rotation speed of the servo motor 54, and this encoder 56 is electrically connected to the control unit 100.

[0027] (Pressure bar mechanism) The configuration of the pressing bar mechanism 60 will be explained with reference to Figures 1 and 4. The pressing bar mechanism 60 is provided with a slider 61 that bends in a horizontal L-shape, and a pressing bar 62 and a first bar 63 are vertically supported on this slider 61, which are arranged parallel to each other along the Y-axis. Here, the pressing bar 62 is a plate member that bends in an inverted L-shape and has a horizontal part 62A and a vertical part 62B, with the lower end of the vertical part 62B forming a sharp knife edge. Furthermore, a spacing adjustment mechanism 64, which constitutes a first pressing bar movement mechanism that moves the pressing bar 62 horizontally in the Y-axis direction, is interposed between the horizontal part 62A of the pressing bar 62 and the slider 61.

[0028] Furthermore, the vertical first bar 63, which is positioned parallel to the pressing bar 62 along the X-axis direction (perpendicular to the plane of the paper in Figure 4), is a plate member that is bent in an inverted L-shape. An axis 65 extending upward from its upper end vertically passes through the slider 61, and a damper 66 is attached to the upper end of the axis 65 that protrudes upward from the slider 61. The damper 66 is composed of an air cylinder and a coil spring, and performs the function of biasing the first bar 63 downward with a constant force.

[0029] The pressing bar 62 and the first bar 63 are movable up and down in the Z-axis direction by a pressing bar lifting mechanism 70 which constitutes a second pressing bar moving mechanism. As shown in Figure 1, the pressing bar lifting mechanism 70 includes a pair of guide rails 72 mounted parallel to each other along the Z-axis direction on a rectangular plate-shaped vertical base 71 fixed to a gate-type column 210, a rotatable ball screw 73 positioned along the Z-axis direction between these guide rails 72, and a servo motor 74, which is a rotational drive source connected to the upper end of the ball screw 73. Here, the lower end of the ball screw 73 is rotatably supported by a base 200 via a bearing (not shown), and the ball screw 73 is screwed into a nut member (not shown) attached to a slider 61. Also, as shown in Figure 1, an encoder 75 for detecting the rotation direction and rotation speed of the servo motor 74 is attached to the servo motor 74, and this encoder 75 is electrically connected to the control unit 100.

[0030] In this embodiment, the second bar lifting mechanism 50 and the pressing bar lifting mechanism 70 constitute a clamping mechanism that brings the first bar 63 and the second bar 31 closer together or further apart. As will be described later, the wafer W is clamped by the first bar 63 and the second bar 31, which are in contact with the upper and lower surfaces, respectively, at the splitting starting point g.

[0031] Therefore, when the servo motor 74 is started and the ball screw 73 is rotated forward and backward, the slider 61, to which a nut member (not shown) that screws onto the ball screw 73 is attached, moves up and down in the Z-axis direction along a pair of guide rails 72, causing the pressing bar 62 and the first bar 63 attached to the slider 61 to move up and down together in the Z-axis direction. The rotation direction and rotation speed of the servo motor 74 are detected by the encoder 75, and when the detection signal is transmitted to the control unit 100, the control unit 100 controls the servo motor 74 based on the received detection signal.

[0032] (Ultrasonic vibration unit) The ultrasonic vibration application unit 80 applies ultrasonic vibration to the pressing bar 62 during the wafer W splitting process described later, and consists of an ultrasonic transducer 81 provided in the middle of the vertical portion 62B of the pressing bar 62 in the height direction, and a high-frequency power supply 82 for supplying high-frequency power to the ultrasonic transducer 81. Here, as shown in Figure 1, the high-frequency power supply 82 is attached to the gantry column 210, and a power cord 83 extending from the high-frequency power supply 82 is electrically connected to the ultrasonic transducer 81 provided on the pressing bar 62.

[0033] (Input device) The input device 90 is a device that allows the operator to input initial setup data such as chip size, wafer material and thickness, and constitutes the initial setup unit. As shown in Figure 1, the data such as chip size, wafer material and thickness input to the input device 90 is transmitted to the control unit 100.

[0034] (Control Unit) The control unit 100 includes a CPU (Central Processing Unit) that performs calculations according to a control program, and a storage unit such as ROM (Read Only Memory) and RAM (Random Access Memory). As shown in Figure 1, the control unit 100 includes an angle setting unit 101 that sets the angle θ (see Figure 7) at which the wafer W is bent along the splitting starting point g, a pressing position setting unit 102 that sets the pressing position O (see Figure 7) of the wafer W by the pressing bar 62, and a pressing bar movement amount calculation unit 103 that calculates the amount of movement of the pressing bar 62 by the spacing adjustment mechanism 64 based on the pressing position O set by the pressing position setting unit 102 and the angle θ set by the angle setting unit 101.

[0035] [Wafer splitting method] <First Embodiment> Next, a method for dividing a wafer W according to the first embodiment of the present invention, which is carried out using the dividing apparatus 1 configured as described above, will be explained. 1) Initial setting process: 2) Holding process: 3) Clamping process: 4) Splitting process: This method involves sequentially performing the following steps in this order to divide a wafer W and obtain multiple chips. Each step will be explained sequentially below in accordance with Figures 4 to 8.

[0036] 1) Initial setting process: The initial setup process is a step in which the operator inputs initial setup data such as the chip size, wafer material and thickness to the input device 90 shown in Figure 1 (step S1 in Figure 8), and the chip size, wafer material and thickness input to the input device 90 are transmitted to the control unit 100.

[0037] Then, the angle setting unit 101 provided in the control unit 100 sets the bending angle θ (see Figure 7) of the wafer W based on the material and thickness of the wafer W input to the input device 90, using a matrix-shaped angle measurement data (map) created based on the material and thickness (step S2 in Figure 8). Note that the angle θ may be determined in advance by conducting an experiment and set by inputting that value using the input device 90. In this embodiment, the operator manually inputs the material and thickness of the wafer W into the input device 90, but the control unit 100 may also be provided with a material setting unit and a thickness setting unit (both not shown), and the bending angle θ of the wafer w may be automatically read from the angle measurement data (map) based on the material and thickness of the wafer W automatically input into these material setting unit and thickness setting unit.

[0038] Incidentally, the control unit 100 may be provided with a first thickness calculation unit (not shown), and as described later, the thickness of the wafer W, whose upper and lower surfaces are clamped by the first bar 63 which moves up and down by the pressing bar lifting mechanism 70 which constitutes the clamping mechanism, and the second bar 31 which moves up and down by the second bar lifting mechanism 50 which also constitutes the clamping mechanism, may be calculated by the first thickness calculation unit based on the detected values ​​of the encoder 75 of the pressing bar lifting mechanism 70 and the encoder 56 of the second bar lifting mechanism 50.

[0039] Furthermore, the pressing position setting unit 102 provided in the control unit 100 sets the pressing position O of the pressing bar 62 based on the chip size input to the input device 90 (step S3 in Figure 8). Here, the pressing position O of the pressing bar 62 (see Figure 7) is a position that is a distance L in the planar direction (Y-axis direction) of the wafer W from the starting point g of the wafer W. The pressing position O may also be set by inputting a value using the input device 90. Alternatively, the control unit 100 may be provided with a chip size setting unit (not shown), and the corresponding pressing position O may be set based on the chip size automatically set by the chip size setting unit of the control unit 100 from the pressing position measurement data (map) based on the chip size and pressing position stored in the control unit 100.

[0040] As described above, when the angle setting unit 101 sets the bending angle θ of the wafer W and the pressing position setting unit 102 sets the pressing position O (distance L) of the pressing bar 62, the pressing bar movement amount calculation unit 103 directed to the control unit 100 calculates the amount of movement (downward movement) ΔZ of the pressing bar 62 using the following formula: ΔZ = L·tanθ …(1) This is calculated by (step S4 in Figure 8).

[0041] 2) Holding process: In the holding process, as shown in Figure 4, the workpiece set WS is placed on the holding table 10, and with the outer circumference of the ring frame F of the workpiece set WS in contact with the two fixed clamps 11, the pressers 12a of the other two movable clamps 12 are moved radially inward on the holding table 10, pressing the outer circumference of the ring frame F against the two fixed clamps 11, thereby holding the ring frame F (i.e., the workpiece set WS) in a positioned state on the holding table 10.

[0042] Furthermore, within the wafer W, multiple linear, vertical splitting points g are formed in a grid pattern by modified layers along streets L1 and L2 (see Figure 2). That is, when a laser beam with a wavelength that is transparent to the wafer W is focused into the interior of the wafer W and irradiated along streets L1 and L2, vertical modified layers are partially formed within the wafer W along streets L1 and L2, and these modified layers are designated as splitting points g. Here, a modified layer is a region whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding area.

[0043] 3) Clamping process: In the clamping process, the holding table 10 and the wafer W (workset WS) held therein move in the Y-axis direction toward the splitting starting point g of the wafer W by the horizontal movement mechanism 20 shown in Figure 1 (step S5 in Figure 8). At this time, as shown in Figure 4, the first bar 63, the second bar 31, and the pressing bar 62 are all positioned vertically separated from the wafer W.

[0044] As described above, when the wafer W is moving in the Y-axis direction, the surface of the wafer W is imaged by an imaging unit (not shown), and the image obtained by imaging is subjected to image processing such as pattern matching to detect the positions of streets L1 and L2, that is, the division starting point g. Then, the control unit 100 determines whether the first bar 63 and the second bar 31 have reached the position where the division starting point g of the wafer W has been formed (step S6 in Figure 8). As a result of this determination, as shown in Figure 4, if the first bar 63 and the second bar 31 have reached the position where the division starting point g of the wafer W has been formed (step S6: Yes), the first bar 63 and the first bar 62 are lowered by the pressing bar lifting mechanism 70 (step S7), and the second bar 31 is raised by the second bar lifting mechanism 50. If the first bar 63 and the second bar 31 have not reached the position where the splitting starting point kg of the wafer W is formed (step S6: No), the movement of the wafer W in the Y-axis direction continues.

[0045] Then, when the descending first bar 63 and the rising second bar 31 come into contact with the upper and lower surfaces of the wafer W, the portion of the wafer W where the splitting starting point g is formed is sandwiched between the first bar 63 and the second bar 31, as shown in Figure 5.

[0046] 4) Splitting process: In the splitting process, it is determined whether the knife-edge-shaped lower end of the pressing bar 62 has come into contact with the upper surface of the wafer W (step S8 in Figure 8). As shown in Figures 6 and 7, the contact detection unit detects whether the knife-edge-shaped lower end of the pressing bar 62 has come into contact with the upper surface of the pressing position O, which is offset by a predetermined distance L in the -Y axis direction from the splitting starting point g of the wafer W. For example, this can be determined by the sudden increase in the current supplied to the servo motor 74 due to the increase in contact resistance caused by the contact of the pressing bar 62 with the wafer W, or by the output of a piezoelectric element (not shown) that measures the load P (see Figure 7) acting on the wafer W from the pressing bar 62. An ultrasonic transducer 81 may also be used to measure the load P.

[0047] Incidentally, the control unit 100 may be provided with a second thickness calculation unit (not shown) so that the second thickness calculation unit calculates the thickness of the wafer W at the time the pressing bar 62 contacts the upper surface of the wafer W based on the output value of the encoder 75 of the pressing bar lifting mechanism 70. Then, the thickness of the wafer W calculated in this way by the second thickness calculation unit may be set as the thickness of the wafer W by a thickness setting unit (not shown) provided in the control unit 100.

[0048] As shown in Figure 5, when the knife-edge lower end of the pressing bar 62 contacts the pressing position O on the upper surface of the wafer W (Step S8: Yes), the pressing bar 62 continues to descend and the wafer W is pressed by the pressing bar 62 with a load P at the pressing position O. At the same time, the amount of movement (pressure) of the pressing bar 62 is detected by the encoder 75 provided on the pressing bar lifting mechanism 70 (Step S9 in Figure 8). If the lower end of the pressing bar 62 is not in contact with the upper surface of the wafer W (Step S8: No), the first bar 63 and the pressing bar 62 continue to descend.

[0049] As described above, when the pressing bar 62 descends while pressing the pressing position O on the upper surface of the wafer W with a load P, the wafer W is bent downward along the splitting starting point g, as shown in Figures 6 and 7. At this time, ultrasonic vibration is applied to the pressing bar 62 from the ultrasonic vibration application unit 80. That is, when the high-frequency power supply 82 of the ultrasonic vibration application unit 80 is turned ON and high-frequency power is applied to the ultrasonic transducer 81 via the power cord 83, the ultrasonic transducer 81 is activated (excited) and the pressing bar 62 vibrates ultrasonically.

[0050] As described above, when the pressing bar 62 is descending while pressing the pressing position O on the upper surface of the wafer W with a load P, the control unit 100 determines whether the amount of movement of the pressing bar 62 detected by the encoder 75 of the pressing bar lifting mechanism 70 has reached a predetermined amount of movement (calculated value) ΔZ calculated by the pressing bar movement amount calculation unit 103 based on equation (1) above (step S10 in Figure 8).

[0051] If, as a result of the above determination, the amount of movement of the pressing bar 62 reaches the calculated value ΔZ (step S10: Yes), the movement of the pressing bar 62 is stopped (step S11). In this way, when the pressing bar 62 moves (descends) by a predetermined calculated value ΔZ, the wafer W is bent and divided by a predetermined angle θ (the angle set in the angle setting unit 101 of the control unit 100) along the division starting point g, as shown in Figure 7. Here, the angle θ is a constant value even if the chip size is different, and is set to a value that is necessary and sufficient to ensure that the wafer W is reliably cut along the division starting point g. If the amount of movement of the pressing bar 62 has not reached the calculated value ΔZ (step S10: No), the movement (descending) of the pressing bar 62 and the detection of the amount of movement continue.

[0052] Then, when the splitting along one street L1 (splitting starting point g) of the wafer W is completed, the first bar 63 and the first bar 62 are raised by the pressing bar lifting mechanism 70 and move to the position shown in Figure 4, which is separated upward from the wafer W (step S12 in Figure 8).

[0053] As described above, once the division along one street L1 is completed, the holding table 10 and the wafer W held therein move in the Y-axis direction (indexing direction) by one pitch (distance between adjacent streets L1) by the horizontal movement mechanism 20 shown in Figure 1, and the same division of the wafer W is performed similarly for the next street L1. After that, it is determined whether or not the division along all of the streets L1 in one direction of the wafer W has been completed (step S13 in Figure 8). If the division along all of the streets L1 in one direction has been completed (step S13 in Figure 8: Yes), the series of processes ends (step S14 in Figure 8). On the other hand, if the division along all of the streets L1 on one side of the wafer W has not been completed (step S13: No), the processes in steps S5 to S13 are repeated.

[0054] As described above, once the splitting along all streets L1 on one side of the wafer W is complete, the holding table 10 and the wafer W (workset WS) held therein are rotated by a rotation mechanism (not shown) by an angle of 90° around a vertical axis, and the splitting along the other street L2, which is orthogonal to the other street L1, is similarly performed. When the wafer W has been split along all streets L2 on the other side, the series of splitting operations on the wafer W is complete, and multiple chips are obtained from the splitting of this wafer W.

[0055] As described above, according to the splitting method of this embodiment, when the bending angle θ of the wafer W is set in the angle setting unit 101 provided in the control unit 100 and the pressing position O of the pressing bar 62 is set in the pressing position setting unit 102, the distance L from the splitting starting point g to the pressing position O of the pressing bar 62 is determined, and the amount of movement ΔZ of the pressing bar 62 is calculated by the pressing bar movement amount calculation unit 103 of the control unit 100 based on equation (1) above, using this distance L and the bending angle θ of the wafer W. This amount of movement ΔZ of the pressing bar 62 is proportional to the chip size, and becomes larger as the chip size increases, but the bending angle θ of the wafer W centered on the splitting starting point g is kept constant.

[0056] In other words, regardless of the chip size, the wafer W is bent at a predetermined (constant) bending angle θ that is necessary and sufficient for division around the division starting point g. This prevents division errors caused by insufficient or excessive movement of the pressing bar 62, and ensures that the wafer W is always reliably divided along the division starting point g. Here, the amount of movement ΔZ of the pressing bar 62 is calculated by the bending angle θ of the wafer W and the distance L (a value determined by the chip size) from the division starting point g to the pressing position O of the pressing bar 62. This allows for quick setting of processing conditions and efficient division of the wafer W in a short amount of time.

[0057] <Second Embodiment> Next, a second embodiment of the wafer W division method according to the invention will be described, but this division method is similar to the first embodiment described above. 1) Initial setting process: 2) Holding process: 3) Clamping process: 4) Splitting process: This method involves sequentially performing the steps in this order to divide the wafer W and obtain multiple chips. Each step will be explained below based on Figures 9 to 11. In Figures 9 to 11, the same reference numerals are used for elements that are the same as those shown in Figures 4 to 6, and further explanation of these elements will be omitted below.

[0058] 1) Initial setting process: The initial setup step in the division method according to the second embodiment is the same as the initial setup step in the first embodiment, so a further explanation of it will be omitted.

[0059] 2) Holding process: In the holding process, as shown in Figure 9, the workpiece set WS is placed on the holding table 10, and with the outer circumference of the ring frame F of the workpiece set WS in contact with the two fixed clamps 11, the pressers 12a of the other two movable clamps 12 are moved radially inward on the holding table 10, pressing the outer circumference of the ring frame F against the two fixed clamps 11, thereby holding the ring frame F (i.e., the workpiece set WS) in a positioned state on the holding table 10.

[0060] In this embodiment, the protective film f wound on the supply roll R1 is pulled out and wound up by the take-up roll R2, but the protective film f between the two rolls R1 and R2 is pressed against the wafer W by two guide rollers r and pressure bars 62 and 1 and 63, and is under tension above the wafer W.

[0061] 3) Clamping process: In the clamping process, as shown in Figure 10, the second bar 31 is raised by the second bar lifting mechanism 50, and the tip of the second bar 31 contacts the lower surface of the wafer W at a position aligned with street L1 or L2 (splitting point g) via the sheet T. Furthermore, the slider 61, the supporting pressing bar 62, and the first bar 63 are lowered by the pressing bar lifting mechanism 70, and the lower surface of the first bar 63 contacts the upper surface of the wafer W at a position aligned with street L1 or L2 (splitting point g) via the protective film f, while the pressing bar 62 contacts the upper surface of the wafer W at a position offset in the -Y axis direction from the splitting point g via the protective film f. Therefore, the wafer W is clamped by the first bar 63 and the second bar 31 at the portion where the splitting point g is formed, via the protective film f and the sheet T.

[0062] 4) Splitting process: In the splitting process, as shown in Figure 11, ultrasonic vibration is applied from the ultrasonic vibration unit 80 to the pressing bar 62, whose knife-edge-shaped lower end contacts the upper surface of the wafer W at a position offset in the -Y axis direction from the splitting starting point g, and presses the upper surface with a predetermined force. In other words, when the high-frequency power supply 82 of the ultrasonic vibration unit 80 is turned ON and high-frequency power is applied to the ultrasonic transducer 81 via the power cord 83, the ultrasonic transducer 81 is activated (excited) and the pressing bar 62 vibrates ultrasonically, so the wafer W is reliably split starting from the splitting starting point g by brittle fracture (fatigue fracture due to repeated stress) caused by the vibration energy propagated from the pressing bar 62.

[0063] In this embodiment, the upper surface of the portion of the wafer W that is divided in the dividing process, including the dividing point g, is covered with a protective film f, as shown in Figure 11. Therefore, the device D is protected by the protective film f, and the scattering of dividing powder generated by the dividing of the wafer W into the surrounding area is prevented by the protective film f.

[0064] Once the division along one street L1 is complete, the division is carried out similarly for the next street L1, as in the first embodiment. When the division along all of the one street L1 on the wafer W is complete, the holding table 10 and the wafer W (workset WS) held therein are rotated by a rotation mechanism (not shown) by an angle of 90° around a vertical axis, and the division along the other street L2, which is orthogonal to one street L1, is carried out similarly. When the wafer W is divided along all of the other street L2, the series of division operations on the wafer W is complete, and multiple chips are obtained by the division of this wafer W. In this embodiment as well, the same effects as those obtained in the first embodiment are obtained.

[0065] In the embodiments described above, the modified layer formed inside the wafer W by laser irradiation was used as the splitting starting point g. However, other methods for forming the splitting starting point g on the wafer W may be used, such as cutting the wafer W along the street with a cutting blade to form cutting grooves (kerfs) (blade dicing), plasma dicing which forms grooves along the street on the wafer W by plasma etching under vacuum, or laser ablation which forms grooves along the street on the wafer W by irradiating the surface of the wafer W with a laser beam.

[0066] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of Symbols]

[0067] 1: Dividing device, 10: Holding table, 11: Fixed clamp, 12: Movable clamp, 12a: Presser for movable clamp, 20: Horizontal movement mechanism, 21: Slider, 22: Guide rail, 23: Ball screw, 24: Servo motor, 25: Nut component, 26: Encoder, 30: Second bar mechanism, 31: Second bar, 40: Second bar rotation mechanism, 41: Rotating shaft, 42: Frame, 43: Driven gear, 44: Electric motor, 44a: Output shaft, 45: Drive gear, 50: Second bar lifting mechanism (clamping mechanism), 51: Base, 52: Guide rail, 53: Ball screw, 54: Servo motor, 55: Bearing 56: Encoder, 60: Pressure bar mechanism, 61: Slider, 62: Pressure bar, 62A: Horizontal part of the pressure bar, 62B: Vertical part of the pressure bar, 63: First bar, 64: Spacing adjustment mechanism (first pressure bar movement mechanism), 65: Shaft, 66: Damper, 70: Pressing bar lifting mechanism (second pressing bar moving mechanism, clamping mechanism), 71: Base, 72: Guide rail, 73: Ball screw, 74: Servo motor, 75: Encoder, 80: Ultrasonic vibration unit, 81: Ultrasonic transducer, 82: High-frequency power supply, 83: Power cord, 90: Input device (initial setting unit), 100: Control unit, 101: Angle setting unit, 102: Pressing position setting unit, 103: Pressing bar movement amount calculation unit, 200: Base, 210: Gantry column, D: Device, F: Ring frame, f: protective film, g: splitting point, L: distance between splitting point and pressure point: L1, L2: Street, O: Pressing position, P: Load, R1, R2: Roll r: guide roller, S: metal film, T: sheet, W: wafer, WS: workset ΔZ: Distance of the pressure bar (calculated value), θ: Wafer bending angle

Claims

1. A method for dividing a wafer having multiple linear division starting points formed on it, by dividing the wafer at the division starting points, An angle setting step to set the angle at which the wafer is bent at the dividing point, A clamping step in which the wafer is clamped by bringing the first bar into contact with one side of the wafer and the second bar into contact with the other side of the wafer, A splitting step is performed in which the wafer, which is clamped between the first bar and the second bar, is bent by an angle set in the angle setting step using a pressing bar to split the wafer at the splitting starting point, A method for splitting a wafer, including [specific details omitted].

2. The wafer splitting method according to claim 1, wherein ultrasonic vibration is applied to the pressing bar in the splitting step.

3. A splitting apparatus for splitting a wafer, which has multiple linear splitting starting points formed on it, at the splitting starting points, A first bar that contacts one side of the wafer, A second bar that faces the first bar across the wafer and contacts the other side of the wafer, A clamping mechanism that moves the first bar and the second bar closer together or further apart, A pressing bar that presses one pressing position on the wafer, which is located a predetermined distance in the planar direction of the wafer from the wafer clamping position by the first bar and the second bar, A first pressing bar moving mechanism moves the pressing bar in a direction perpendicular to the direction of extension of the pressing bar in the planar direction of the wafer, A second pressing bar moving mechanism moves the pressing bar in a direction perpendicular to the wafer plane direction, An angle setting unit for setting the angle at which the wafer is bent at the dividing point, A pressing position setting unit for setting the pressing position of the wafer by the pressing bar, A pressing bar movement amount calculation unit calculates the amount of movement of the pressing bar by the second pressing bar movement mechanism based on the pressing position set by the pressing position setting unit and the angle set by the angle setting unit. A dividing device equipped with the following features.

4. A material setting unit for setting the wafer material, A thickness setting unit for setting the wafer thickness, Equipped with, The splitting apparatus according to claim 3, wherein the angle setting unit sets the corresponding wafer bending angle based on the wafer material set by the material setting unit and the wafer thickness set by the thickness setting unit, from matrix-like angle measurement data based on the wafer material and thickness.

5. It includes a chip size setting unit for setting the size of the chip formed by the wafer division, The dividing device according to claim 4, wherein the pressing position setting unit sets the corresponding pressing position based on the size of the chip set by the chip size setting unit, using pressing position measurement data based on the size of the chip and the pressing position.

6. The splitting device according to claim 3, further comprising an ultrasonic transducer for ultrasonically vibrating the pressing bar.

7. The clamping mechanism includes a first thickness calculation unit that calculates the thickness of the wafer, The dividing device according to claim 4, wherein the thickness setting unit sets the thickness calculated by the thickness calculation unit.

8. A contact detection unit detects when the pressing bar, which has been moved by the second pressing bar moving mechanism, has come into contact with one side of the wafer. A second thickness calculation unit calculates the wafer thickness using the contact detection unit, Equipped with, The dividing apparatus according to claim 4, wherein the thickness setting unit sets the value calculated by the second thickness calculation unit as the thickness of the wafer.

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